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Re: Avoiding a for cicle [message #19636 is a reply to message #19627]

Tue, 11 April 2000 00:00

Benno Puetz
Messages: 16
Registered: March 2000

Junior Member

<!doctype html public "-//w3c//dtd html 4.0 transitional//en">
<html>
"J.D. Smith" wrote:
<blockquote TYPE=CITE>Ricardo Fonseca wrote:
 >
 > Hi
 >
 > I'm looking for a more efficient way of implementing the following
(i.e.
 > avoiding the for cycle) which is a routine for finding local maximuns
 >
 > ; Data is a 1D Array
 >
 > s = Size(Data)
 >
 > nx = s[1]
 >
 > max_pos = [-1]
 >
 > for i = 1, nx-1 do $
 >    if ((Data[i] gt Data[i-1]) and (Data[i] gt Data[i+1]))
then $
 >          max_pos = [[max_pos],i]
 >
 > ; and then throw away the first element...
max_pos = where(data gt median(data,3))
  </blockquote>
While this is rather efficient concerning code length,
  
<pre> maxpos = WHERE(TEMPORARY(data[0:nx-3]) LT TEMPORARY(data[1:nx-2]) AND  $</pre>

<pre>                   TEMPORARY(data[1:nx-2]) GT TEMPORARY(data[2:nx-1])) + 1</pre>

<pre></pre>
should execute faster, especially for longer arrays
 --  
Benno Puetz 
Kernspintomographie 
Max-Planck-Institut f. Psychiatrie    &nbsp ;     &nbsp ;
Tel.: +49-89-30622-413 
Kraepelinstr. 10     &nbs p;     &nbs p;     &nbs p;     &nbs p;     
Fax : +49-89-30622-520 
80804 Muenchen, Germany
  </html>

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[Message index]

		Re: Avoiding a for cicle By: John-David T. Smith on Tue, 11 April 2000 00:00
		Re: Avoiding a for cicle By: davidf on Tue, 11 April 2000 00:00
		Re: Avoiding a for cicle By: John-David T. Smith on Tue, 11 April 2000 00:00
		Re: Avoiding a for cicle By: Craig Markwardt on Tue, 11 April 2000 00:00
		Re: Avoiding a for cicle By: Benno Puetz on Tue, 11 April 2000 00:00
		Re: Avoiding a for cicle By: John-David T. Smith on Fri, 07 April 2000 00:00
		Re: Avoiding a for cicle By: landsman on Fri, 07 April 2000 00:00
		Re: Avoiding a for cicle By: Med Bennett on Thu, 06 April 2000 00:00

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